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modula-2: Amend the handling of failed select() calls in RTint [PR108835].

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When we make a select() that fails, there is an attempt to (a) diagnose
why and (b) make a fallback.  These actions are causing some tests to
hang on some Darwin versions, this is because the first action that is
tried to assist in diagnosis/fallback handling is to replace the set
timeout with NIL (which causes select to wait forever, modulo other
reasons it might complete).

To fix this, call select with a zero timeout when checking for error
conditions.  Also, as we check the possible failure conditions, if we
find a change that succeeds, then stop looking for errors.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

	PR testsuite/108835

gcc/m2/ChangeLog:

	* gm2-libs/RTint.mod: Do not use NIL timeout setting on select,
	test failures sequentially, finishing on the first success.
This commit is contained in:
Iain Sandoe 2023-02-25 23:18:13 +00:00
parent d6a6a4ea08
commit ef4ea6e087
1 changed files with 54 additions and 16 deletions
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70
gcc/m2/gm2-libs/RTint.mod
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@ -441,6 +441,10 @@ END ExcludeVector ;
PROCEDURE AddFd (VAR set: SetOfFd; VAR max: INTEGER; fd: INTEGER) ;
BEGIN
IF (fd<0)
THEN
RETURN
END ;
max := Max (fd, max) ;
IF set = NIL
THEN
@ -667,6 +671,7 @@ PROCEDURE Listen (untilInterrupt: BOOLEAN;
VAR
found : BOOLEAN ;
result : INTEGER ;
zero,
after,
b4,
timeval: Timeval ;
@ -722,14 +727,14 @@ BEGIN
THEN
SetTime (timeval, 0, 0)
END ;
IF untilInterrupt AND (inSet=NIL) AND (outSet=NIL) AND (NOT found)
IF untilInterrupt AND (((inSet=NIL) AND (outSet=NIL)) OR (maxFd=-1)) AND (NOT found)
THEN
Halt ('deadlock found, no more processes to run and no interrupts active',
__FILE__, __FUNCTION__, __LINE__)
END ;
(* printf('timeval = 0x%x\n', timeval) ; *)
(* printf('}\n') ; *)
IF (NOT found) AND (maxFd=-1) AND (inSet=NIL) AND (outSet=NIL)
IF (NOT found) AND (maxFd=-1)
THEN
(* no file descriptors to be selected upon. *)
timeval := KillTime (timeval) ;
@ -738,6 +743,7 @@ BEGIN
ELSE
GetTime (timeval, sec, micro) ;
Assert (micro < Microseconds) ;
zero := InitTime (0, 0) ;
b4 := InitTime (0, 0) ;
after := InitTime (0, 0) ;
result := GetTimeOfDay (b4) ;
@ -754,26 +760,54 @@ BEGIN
THEN
printf ("select (.., .., .., %u.%06u)\n", sec, micro)
END ;
result := select (maxFd+1, inSet, outSet, NIL, timeval) ;
IF maxFd<0
THEN
result := select (0, NIL, NIL, NIL, timeval)
ELSE
result := select (maxFd+1, inSet, outSet, NIL, timeval)
END ;
IF result=-1
THEN
perror ("select") ;
result := select (maxFd+1, inSet, outSet, NIL, NIL) ;
IF result=-1
IF Debugging
THEN
perror ("select timeout argument is faulty")
perror ("select failed : ") ;
END ;
result := select (maxFd+1, inSet, NIL, NIL, timeval) ;
IF result=-1
result := select (maxFd+1, inSet, outSet, NIL, zero) ;
IF result#-1
THEN
perror ("select output fd argument is faulty")
END ;
result := select (maxFd+1, NIL, outSet, NIL, timeval) ;
IF result=-1
THEN
perror ("select input fd argument is faulty")
GetTime (timeval, sec, micro) ;
IF Debugging
THEN
printf ("(nfds : %d timeval: %u.%06u) : \n", maxFd, sec, micro) ;
END ;
perror ("select timeout argument was faulty : ")
ELSE
perror ("select maxFD+1 argument is faulty")
result := select (maxFd+1, inSet, NIL, NIL, timeval) ;
IF result#-1
THEN
perror ("select output fd argument was faulty : ")
ELSE
result := select (maxFd+1, NIL, outSet, NIL, timeval) ;
IF result#-1
THEN
perror ("select input fd argument was faulty : ")
ELSE
IF maxFd=-1
THEN
result := select (0, NIL, NIL, NIL, timeval) ;
IF result=-1
THEN
IF Debugging
THEN
perror ("select does not accept nfds == 0 ") ;
END ;
result := 0
END
ELSE
perror ("select maxFD+1 argument was faulty : ") ;
END
END
END
END
END
UNTIL result#-1
@ -785,6 +819,10 @@ BEGIN
THEN
timeval := KillTime (timeval)
END ;
IF zero#NIL
THEN
zero := KillTime (zero)
END ;
IF after#NIL
THEN
after := KillTime (after)